Telescopes in Low Vision

Question 1

What is low vision?

Answer 1

Visual acuity less than 6/18 and equal to or better than 3/60 in the better eye, with best correction or visual fields less than 20 degrees in diameter

Question 2

Why are telescopes used for low vision?

Answer 2

They increase the angular subtense without requiring a change in working distance
- They are the only visual aid for distance magnification

Question 3

Why are the telescopes good for low vision?

Answer 3

• Good for far and intermediate distances: Spotting a bus, reading and music
• Good for near tasks with a longer working distance

Question 4

What are the positive and negative telescopes?

Answer 4

• positive lens (Keplerian)
  -negative lens (Galileo)

Question 5

What is the exit pupil?

Answer 5

• Image of the objective as seen through the eyepiece/ocular.
• All light entering the objective telescope will exit the exit pupil